Zelkova 'Verschaffeltii'

Zelkova ‘Verschaffeltii’ was growing at the van Houtte nursery in Belgium by 1886, when an example was purchased by the Royal Botanic Gardens, Kew (Bean 1981; Wikipedia 2023). TIts origins long remained a mystery, and it was only confirmed as a zelkova when a specimen at Paris fruited in 1908 (Bean 1981). Leopold Dippel suspected an east Asian origin in 1892 when he named it in honour of the late Belgian botanist Ambroise Verschaffelt, but opinion eventually prevailed that this was an accidental hybrid of Z. carpinifolia with either Z. abelicea or Z. serrata (Elwes & Henry 1906–1913; Bean 1981). In 1983, Frank Santamour found that it contained a flavonol (quercetin 7-glucoside) that seemed otherwise unique to Z. serrata, as well as flavonoids otherwise unique to Z. carpinifolia (Santamour 1983). Many sources, including Plants of the World Online (Royal Botanic Gardens Kew 2023) consequently prefer to call the tree Z. × verschaffeltii, but it makes more sense to treat it as a clone: were the cross between Z. carpinifolia and Z. serrata to occur again, there is no expectation that the offspring should have the suite of unusual features which Dippel described in van Houtte’s tree (in particular, the lobed and long-stalked leaves with significantly fewer pairs of major veins than either parent).

The lobing of the cut leaves is not deep enough to create a distinctively soft or feathery foliage effect, but like the rest of its genus Zelkova ‘Verschaffeltii’ is a pretty tree, with a colourfully flaking bark. Although scarcely known in North America, it is still sometimes grown in western Europe, and there is also an example in the Jerusalem Botanical Gardens (Jerusalem Botanical Gardens 2023). It is characteristically a weaker plant than either presumed parent, and is often multistemmed and appears short-lived. Curiously, the UK champion, at Crathes Castle in eastern Scotland, is the northernmost zelkova of real note but has made a sturdy and handsome domed tree which, in this relatively harsh microclimate, can show brilliant autumn colours; in 2018 it was 11 m tall with a single bole 53 cm dbh (Tree Register 2023; ‘I can now retire – fulfilled’ – American dendrologist Michael Dirr, upon making the pilgrimage to see this tree (Dirr 2009).) To create a single-stemmed specimen, ‘Verschaffeltii’ is sometimes sold as a high graft on a stem of Z. serrata; one such, in Walsall Arboretum, a public park in the English West Midlands, is the survivor of three, the others having been fatally ring-barked by gnawing squirrels (Tree Register 2023).